1. Field of the Invention
The present invention relates to an anchor device for anchoring a ship or boat.
2. Related Art Statement
In order to anchor a ship fixedly at a desired position, an anchor used for such purpose must have large arms and flukes or like means for holding a large amount of sand, soil or like at the bottom of the water or have sharp bills for firmly grasping a rock at the bottom of the water. However, it is often hard to release an anchor having sharp bills from a rock. On the other hand, in order to have a sufficient anchoring power by holding the sand or soil, a large amount of sand or soil should be held by the flukes and arms of the anchor. However, when it is desired to raise the anchor which has held a large amount of sand or soil, the anchor rope must be hoisted by an extremely high power.
As one approach for solving the aforementioned problems, an anchor device shown in FIGS. 14 and 15 has been proposed by Japanese Utility Model Application No. 135965/1975 (laid open to the public by Japanese Utility Model Laid-Open Publication No. 49493/1977). This prior art anchor device 1 comprises a shank 2 having one end formed with an integral fluke 3 bend backwardly and the other end provided with a ring 5. A portion of the ring 5 is cut away to form a slit 4, and a locking lug 6 of a rotatable fitting 7 is retained by the ring 5. As shown in FIG. 14, the locking lug 6 extends substantially along a diametral direction of the ring 5 and confined by the peripheral wall of the ring 5 when the anchor device 1 is in the anchoring position. The fitting 7 is formed with an eyelet at the end opposing to the locking lug 6, and one end of a rope 8 is tied to the eyelet. The end of the fitting 7 provided with the eyelet is also connected with one end of a chain 9, and the other end of the chain 9 is connected to the crown, i.e. the end of the shank 2 from which the bent fluke 3 extends. When the fitting 7 is rotated to the position shown in FIG. 15 and the rope 8 is drawn upwardly, the locking lug 6 passes through the slit 4 so that the fitting 7 is released from the ring 5, as will be readily understood from FIG. 15.
When the anchor device 1 is used in the anchoring position as shown in FIG. 14, the force pulling the rope 8 in the left direction as viewed in FIG. 14 is transmitted through the fitting 7, the ring 5 and the shank 2 to the fluke 3 which resists the pulling force to anchor the ship in position. When it is desired to raise the anchor device 1, the ship is moved so that the fitting 7 is rotated by the rope 8 to align the locking lug 6 with the slit 4, as shown in FIG. 15, to release the locking lug 6 from the ring 5 and to separate the fitting 7 from the end of the shank 2 formed with the ring 5. As the result, the pulling force applied from the rope 8 is transmitted through the chain 9 directly to the crown or the root portion of the fluke 3, so that the fluke 3 is raised with its sharp force end oriented downwardly to make it possible to hoist the rope 8 with a little power.
However, this prior art anchor device has a disadvantage that the ship must be moved to rotate the fitting 7 so as to release the locking lug 6 from the ring 5. Such a locomotion or movement of the ship necessary for separating the fitting 7 from the ring 5 is often impossible, for example, when the ship is stayed in a small bay or near a reef or shore. In such a case, this prior art anchor device cannot exert the designed performance characteristic, and thus fails to take advantage of reducing the power required for hoisting the rope. Another more serious problem involved in this prior art anchor device is the lack of reliability. In detail, if the ship lying at the anchor device is unintentionally moved by the ebb and flow of tide or by the change in current to result in rotation of the fitting 7 at the position shown in FIG. 15, the fitting 7 would be eventually separated from the ring 5 spontaneously, whereupon the grasping force of the anchor device is significantly reduced.
Another proposal has been made by Japanese Utility Model Application No. 132222/1981 (which was laid open to the public by Japanese Utility Model Laid-Open Publication No. 36993/1983). In the anchor device disclosed by this publication, the lower end of a rope is connected to the end of the shank, from which end the grasping flukes The rope is tied to the other end of the shank opposite to said one end by a relatively weak string. With this construction, when any one of the flukes bites into a rock at the bottom of the water to make it extremely hard or even impossible to release the pawl from the rock, a pulling force sufficiently high to break the relatively weak string is applied through the rope to cut the string so as to separate the rope from said other end of the shank, whereupon the pulling force transmitted through the rope is directly applied on the crown end of the shank, i.e. the root ends of the grasping pawls, so that the anchor is raised with the pawls oriented downwardly by a little raising or hoisting force. However, the anchor device of such construction is not reliable, since the relatively weak string is apt to be broken unintentionally, for example, by a violent force of wave or wind at the stormy weather, leading to loss of anchoring function.